class_docstr: Periodic Resource updater for Tune.
  
  Initially, all resources are set to 0. The updater will try to update resources
  when (1) init ResourceUpdater (2) call "update_avail_resources", "num_cpus"
  or "num_gpus".
  
  The update takes effect when (1) Ray is initialized (2) the interval between
  this and last update is larger than "refresh_period"
code: def get_num_cpus(self) -> int:
      self.update_avail_resources()
      return self._avail_resources.cpu
  
imports: import logging
  import os
  import time
  from collections import namedtuple
  from numbers import Number
  from typing import Any, Dict, Optional
  import ray
  from ray._private.resource_spec import NODE_ID_PREFIX
label_desc: Use image node_id 5 for calling the _ResourceUpdater obj's underlying member method code with example usage: obj.get_num_cpus() and returns: self